PubMed Health⌕ Search

Biomedical subjects

F W James

Publications and source records attributed to F W James.

At least 37 records · Page 2Linked to original sources
PubMed1981

Exercise testing in children before and after surgical treatment of aortic stenosis.

Twenty-three children with valvar or discrete subvalvar aortic stenosis underwent a controlled, progressive bicycle exercise test within 6 months before and 3-30 months after surgery for left ventricular outflow tract obstruction. The patients were divided into three groups according to the preoperative resting gradient of left ventricular to aortic peak systolic pressure: 30-69 mm Hg (group A), 70-99 mm Hg (group B), and greater than or equal to 100 mm Hg (group C). Preoperatively, 19 of 23 patients (83%) developed significant ST depression (greater than or equal to 1.0 mm) during exercise, whereas only seven (30%) had abnormal ST depression at rest. Postoperatively, mean exercise-induced ST depression regressed to less than 1 mm in all three groups. In the total population the frequency of ST depression greater than 1 mm was significantly reduced after surgical treatment and mean total work and peak exercise systolic blood pressure were significantly increased within 12 months after surgery. Total work increased significantly in group B within 12 months and in group C within 13-24 months after surgery, but remained unchanged on group A. Peak exercise heart rates were similar before and after surgery in each group. Peak exercise systolic pressures increased after surgery in all three groups, but the mean differences were statistically significant only in group C patients tested 13-24 months after surgery. The results of this study show that exercise testing is useful for quantifying the severity of aortic stenosis and documenting the clinical improvement (or lack thereof) after surgical treatment, and that properly supervised exercise testing can be performed at minimal risk to children with significant aortic stenosis.

Adolescent↗
PubMed1980

Responses of normal children and young adults to controlled bicycle exercise.

Exercise responses were obtained from 149 children and young adults (average age 14.5 years) and divided by sex and body surface area (BSA): children with BSA less than 1 m2; children with BSA 1--1.19 m2; males with BSA greater than or equal to 1.2 m2; and females with BSA greater than or equal to 1.2 m2. Total work, mean and maximal power outputs were more affected by body size (height) than age in children with BSA less than 1 m2 and in males and females with BSA greater than or equal to 1.2 m2. Mean systolic pressure increased up to 64% above the preexercise supine value at peak effort, with the level of mean maximal systolic pressure having a positive relationship with body size (height), power output and preexercise sitting systolic pressure in all subgroups except children with BSA 1--1.19 m2. Mean diastolic pressure increased up to 24% above the preexercise supine value at peak effort. ST-segment depression of 1--2 mm was recorded in 12.1% (18 of 149) of the population at peak exercise. These changes occurred in 8.9% of all males and in 16.9% of all females (p greater than 0.1). The data from this study reveal the importance of sex and body size in the clinical interpretation of exercise responses in growing subjects, provide a reference for objective evaluation of subjects with or without cardiac abnormalities and provide a guide for careful monitoring of subjects during an exercise study.

Adolescent↗
PubMed1978

Exercise testing in children and young adults: an overview.

This chapter has demonstrated the diagnostic capability and feasibility of documenting functional abnormalities during dynamic stress in a pediatric population. The overview confirms that a controlled exercise procedure can be performed routinely in ambulatory children with or without cardiovascular disease and should be included in the clinical evaluation of specific lesions. It now appears that the primary indications for noninvasive exercise testing in the pediatric population include the following disorders: 1. Left ventricular outflow obstructions, a. Subvalvar obstructions, b. Valvar obstructions, c. Supravalvar obstructions, d. Idiopathic hypertrophic subaortic stenosis, e. Coarctation of the aorta; 2. Chronic left or right ventricular volume overload, a. Atrioventricular or semilunar valve incompetence, b. Left-to-right shunts; 3. Rhythm and conduction disturbances, a. Postoperative ventriculotomy, b. Bradytachyarrhythmias, c. Arrhythmias in patients with or without symptoms. The role of the exercise procedure is not yet established in the following areas: 1. Patients with family history of premature atherosclerosis or Type II hyperlipoproteinemia; 2. Patients with elevated blood pressure; 3. The evaluation of syncope, chest pain, or atypical findings on physical examinations (especially in athletes). Consequent upon increased interest and improved technology, the role of this technique will soon be established in the invasive and noninvasive evaluation of pediatric patients with or without overt cardiovascular disease.

Adolescent↗
PubMed1976

Maximal exercise stress testing in normal and hyperlipidemic children.

Electrocardiographic and cardiovascular responses during maximal exercise were evaluated in 103 normal children and in 82 children with familial hyperlipoproteinemia. The normal and hyperlipidemic children were comparable in regards to age, weight--height index, resting and exercise blood pressures, and maximal working capacity indices. The cohort of 82 hyperlipidemic children included 61 children (29 boys and 32 girls) with well defined "monogenic" familial hyperlipoproteinemia. Segmental ST depression on the exercise electrocardiogram occurred in 8 of these 29 boys (27.6%) as compared to 4 of 55 normal boys (7.3%), P less than 0.025 and in 6 of the 32 girls (19%) as compared to 7 of 48 normal girls (14.6%), P greater than 0.1. Segmental ST depression was present in 14 of 61 (23%) children with "monogenic" hyperlipoproteinemia, as compared to 11 of 103 (10.75%) normal (x2 = 4.47, P less than 0.05). An assessment of the clinical significance of an abnormal exercise electrocardiogram in male children with "monogenic" hyperlipoproteinemia must await the following: (1) two to four decades of observation and study of the development of morbid or mortal coronary disease, or (2) the future development of improved invasive or noninvasive techniques for the early detection of covert coronary occlusive disease. Currently, maximal exercise electrocardiography cannot be contemplated as a useful indicator of eventual premature coronary artery disease in asymptomatic hyperlipidemic children.

Adolescent↗
PubMed1976

Response to exercise in patients after total surgical correction of Tetralogy of Fallot.

Heart rate, blood pressure, physical working capacity, and electrocardiographic changes were evaluated during upright bicycle exercise in 43 asymptomatic patients, aged seven to 41 years, one to 14 years after total surgical correction of tetralogy of Fallot (TF). One hundred and nine normal subjects between the ages of five and 42 years served as controls. The patient and control groups, subdivided by sex and body surface area (BSA), were similar in height and weight. When comparing males to males and females to females with BSA greater than or equal to 1.2 m2, maximal heart rates and working capacities were lower in the patient groups than in the control groups. An inverse relationship was observed between maximal working capacity and age at surgery in both male and female patient groups. By contrast, especially in the males with BSA less than 1.2 m2, the mean maximal heart rates and working capacities did not differ significantly between the patient and control groups. Premature atrial or ventricular contractions were recorded in ten of 43 patients (23%) after exercise. Five of these ten patients had multifocal premature ventricular contractions (PVC) and four had unifocal PVC. In the five patients with multifocal PVC, a short burst of ventricular tachycardia occurred in two, coupling in one, and bigeminal rhythm in two. Cardiac arrhythmia was not observed in the control group. Although our current surgical results are excellent, this study suggests that impaired cardiovascular function persists after corrective surgery and that early surgical treatment may be more desirable. Furthermore, additional data suggest that the exercise procedure may be useful in detecting and managing patients who may develop life-threatening arrhythmias following intraventricular surgery.

Adolescent↗
PubMed1975

Unexpected cardiac arrest in patients after surgical correction of tetralogy of Fallot.

Four of 220 patients without bifasicular block (complete right bundle branch block and left anterior hemiblock) or transient complete heart block immediately after surgery had an unexpected cardiac arrest one to 15 years after satisfactory surgical repair of tetralogy of Fallot. The postoperative electrocardiograms (ECG) revealed complete right bundle branch block in two patients and no intraventricle conduction abnormality in two patients. Each of the four patients had premature ventricular contractions on previous postoperative ECG. The cardiac arrest occurred during normal activity in three patients and mild exercise in one. Following the cardiac arrest, three patients died and one patient survived. Eighteen months before the cardiac arrest, the survivor had a stress test which revealed multifocal premature ventricular contractions with short bursts of ventricular tachycardia after exercise. This ventricular arrhythmia was suppressed with quinidine therapy. Although complete heart block cannot be excluded in these four patients, we reasoned that the cardiac arrests were probably preceded by ventricular tachyarrhythmia. Because of this experience, we believe that any patient who has had intraventricular surgery should be evaluated for ventricular arrhythmia. If frequent premature ventricular contractions or serious ventricular arrhythmias are documented, we seriously consider antiarrhythmic therapy in an attempt to prevent ventricular tachyarrhythmias and sudden death.

Adolescent↗
PubMedDate not supplied

Regional myocardial blood flow and cardiac mechanics in dog hearts with CO2 laser-induced intramyocardial revascularization.

Laser-induced intramyocardial revascularization (LIR) has been used to promote direct communications between blood within the ventricular cavity and that of the existing myocardial vasculature in an attempt to increase perfusion in patients with ischemic heart disease. This study was conducted to measure the effects of LIR channels on regional myocardial flood flow (microspheres), cardiac mechanics (sonomicrometers), and myocardial tissue pressures in 18 dogs. Under baseline hemodynamic conditions (mean HR = 165.2 +/- 11.4 bpm, LVP = 123.6 +/- 22.9/4.0 +/- 1.8 mm Hg, AoP = 112.8 +/- 27.1/77.0 +/- 22.5 mm Hg), myocardial blood flow in laser-treated tissue (mean = 1.11 +/- .10 cc/min/gm before laser; .71 +/- .19 cc/min/gm after laser) was reduced as compared to blood flow in control tissue (mean = 1.12 +/- .15 cc/min/gm before laser; 1.25 +/- .22 cc/min/gm after laser). Regional myocardial systolic shortening (11.32% +/- 3.82% before laser; 7.49% +/- 2.86% after laser) was decreased by 33%. During simultaneous reversible ligation of the LAD and LCCA for 2 min, when intramyocardial channels represented the only tissue access for the injected microspheres, blood flow in laser-treated tissue was not increased above that of the control non-lasered tissue. However, regional blood flow was greater in laser-treated ischemic tissue (mean = .61 +/- .12 cc/min/gm) than in untreated ischemic areas (mean = .04 +/- .03 cc/min/gm) when left ventricular pressure (LVP) was acutely elevated (mean SLVP = 207.0 +/- 16.1 mm Hg). Using these measurements, a model is proposed to predict regional systolic pressure gradients between the left ventricular cavity and coronary intramyocardial vasculature required to permit restoration of blood flow to ischemic myocardium. We conclude that improved perfusion via laser-induced intramyocardial channels does not occur in otherwise normal myocardium exposed to acute coronary ligation and only small improvements in perfusion are noted when LVP is significantly elevated. Consideration of further clinical application of this approach is seriously cautioned awaiting additional experimental studies.

Animals↗